Antenna design is a mature technology and many types of antenna structures have been conceived of, constructed, and tested. Antenna propagation characteristics can vary between narrow and broad frequency bands, and between omnidirectional coverage and high-gain, narrow beam width designs.
One antenna type that is popularly utilized is the broad band scanning receiver antenna. A broad band antenna design is well suited for receivers which receive a broad range of frequency. Since scanning receivers are frequently used to receive local broadcasts having relatively strong signals, such as local police transmissions, high gain characteristics are not essential.
Scanning receivers are available in hand-portable, mobile and base configurations. For each of these configurations there is an antenna design which is best suited for the particular application. Direct mounted antennas are well suited for hand-portable scanners. For base scanners, either direct mounted or remotely mounted antennas employing coaxial feed lines to facilitate remote, or elevated, antenna mounting are suitable. Mobile scanning receivers, or any mobile receiver for that matter, are best utilized if a remotely mounted antenna having a feed line is employed. This allows the antenna to be positioned so that radio waves will not be shielded by the metallic structure of the mobile vehicle.
In the case of direct mounted antenna, it is fairly straightforward to design an antenna with good performance characteristics and at low cost. It is commonly known that low cost, collapsible section, antennas have been employed for base scanning radios and other receiver applications.
When marketing a scanning receiver, it is useful to provide an antenna with the receiver so that the receiver can be used immediately upon receipt. Otherwise, a user would have to obtain an antenna from a third party before operating the receiver to receive radio signals. Of course, a user can adapt the receiver to utilize an alternate antenna type, if so desired.
If an antenna is not provided with a mobile scanning receiver, then the user must obtain an antenna and install it into the vehicle in which the receiver is to be used. A professionally installed mobile antenna can be quite expensive. Especially if the combined cost of the antenna and installation are contrasted with the relatively low cost of mass-produced mobile scanning receivers. It is not uncommon for the cost of the installed antenna to exceed the cost of the mobile scanning receiver.
There is a need for a low cost antenna suitable for installation in a vehicle, for receiving radio signals and feeding the signals to a receiver, via a feed line. Further, there is a need for such an antenna which can be easily installed by the end user such that professional installation assistance is not needed.